Scorpions Drummer James Kottak -- My Ex-Wife Is a Drunk, Unfit Mother

Scorpions drummer James Kottak claims his ex-wife is an alcoholic who isn't fit to raise their 15-year-old son ... but she says the rocker is lying in a pathetic effort to reduce his child support payment.

Kottak filed legal docs this month asking a judge to change a July 2011 ruling that gave his ex Athena Lee (Tommy Lee's little sis) primary custody of their teenage son AND ordered him to cough up $1,466 / month in child support and another $1,738 / month in spousal support.

In the docs, filed in L.A. County Superior Court, Kottak claims their son has been living with him 100% of the time since January 2012, when the teenager had a falling out with his mother. Kottack claims Athena has been in and out of rehab for alcohol addiction.

Kottak -- who was married to Athena from 1996 to 2010 -- says he deserves primary physical custody with Athena getting visitation rights. He also wants the court to reduce his child support payments.

The drummer also specifies that his income -- listed at $12,000 month -- isn't set in stone because his contract with the Scorpions has yet to be renewed.

Kottak claims his wife on the other hand makes plenty of money ($3,100 month) and has the potential to pull in $80k / year as a surgical nurse -- so he wants his spousal support cut down too.

But Athena says the rocker is spewing lies -- claiming she's been sober since January 13, 2012 and is allowing her son to live with Kottak so he can stay in his school district.

"He's trying everything he can to knock me down," Athena says ... adding, " It's only about the money to James."